Friction Force & Direction for 925 kg Car at -12.2m/s2 Acceleration

  • Thread starter Thread starter drinkingstraw
  • Start date Start date
  • Tags Tags
    Friction
Click For Summary

Homework Help Overview

The discussion revolves around determining the frictional force and its direction for a car with a specified mass and acceleration. The context involves concepts from dynamics and friction in physics.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants explore the relationship between mass, acceleration, and frictional force, with some suggesting the use of free-body diagrams and equations of motion. Questions arise regarding the coefficient of friction and its role in calculating the frictional force.

Discussion Status

There are multiple lines of reasoning being explored, including the use of free-body diagrams and the relationship between normal force and friction. Some participants provide guidance on focusing on the forces involved without overcomplicating the problem.

Contextual Notes

Participants note the need to find the coefficient of friction and question the assumptions regarding the forces acting on the car, including the normal force and gravitational force.

drinkingstraw
Messages
23
Reaction score
0
The average rate of acceleration for a breaking car was -12.2m/s2. If the car had a mass of 925 kg, find the frictional force and direction.

a = -12.2m/s2
m = 925 kg
Fn = 9074.25 N

This is what I've figured out. I don't know how to find the coefficient of friction. If I get the coefficient I think I can multiply it by the normal force to get the frictional force.
 
Physics news on Phys.org
You're complicating the problem unnecessarily.

The question asks only for the frictional force and direction. Try drawing a free-body diagram for the car and then write down the F=ma equations.
 
F_f = u*F_n

F_n = mgF_f = u *mg

find u
 
The problem only asks for F_f :smile:
The free body diagram is the way to go. Fn and Fg cancel out. What other force or forces provide the acceleration?
 

Similar threads

Newton's law problem: Pushing 2 stacked blocks on a horizontal table
  • · Replies 13 ·
Replies
13
Views
4K
Friction direction change in a inclined circular bend (car on a road)
  • · Replies 11 ·
Replies
11
Views
1K
Coefficient of Friction question for a cart going down a wooden ramp
  • · Replies 18 ·
Replies
18
Views
3K
Friction Forces on 2WD vs 4WD Vehicles
  • · Replies 6 ·
Replies
6
Views
2K
How Do You Calculate Race Car Acceleration and Power Output?
  • · Replies 20 ·
Replies
20
Views
2K
Final Velocity of a car with a opposing decreasing drag force
  • · Replies 57 ·
2
Replies
57
Views
3K
Problem with the power of car
  • · Replies 3 ·
Replies
3
Views
1K
Normal force at the base of a ladder
  • · Replies 20 ·
Replies
20
Views
2K
Why is the direction of kinetic/static friction up a ramp?
  • · Replies 7 ·
Replies
7
Views
2K
For the friction formula when to use Fn(normal force)×mu and when F×mu
  • · Replies 17 ·
Replies
17
Views
3K